Antimicrobial antifoam compositions and methods

ABSTRACT

A defoamer composition including a primary antifoam agent which includes a particulate-type material having a high surface area such as silica, a secondary antifoam agent for acting synergistically with the primary antifoam agent such as polydimethylsiloxane, a water carrier, and a quaternary ammonium salt silane compound which functions as an antimicrobial agent, fixed and adhered to the surface of the particulate material, in order that the defoamer composition be resistant to biological degradation due to the presence in the system of microorganisms. Methods of defoaming cationic, anionic, and nonionic surfactant produced foams are disclosed, as is a method of rendering silica hydrophobic.

RELATED PATENT APPLICATIONS

This application is a continuation-in-part of our prior copendingapplication U.S. Ser. No. 07/221,581, filed July 20, 1988, now abandonedand entitled "Antimicrobial Antifoam Compositions and Methods".

BACKGROUND OF THE INVENTION

This invention relates to an antifoam composition including particulatematerial, the particulate material of the antifoam composition havingadhered thereto an antimicrobial agent which functions to preventbacterial spoilage.

Antimicrobial agents are chemical compositions that are used to preventmicrobiological contamination and deterioration of products, materials,and systems. Particular areas of application of antimicrobial agents andcompositions are, for example, cosmetics, disinfectants, sanitizers,wood preservation, food, animal feed, cooling water, metalworkingfluids, hospital and medical uses, plastics and resins, petroleum, pulpand paper, textiles, latex, adhesives, leather and hides, and paintslurries. Of the diverse categories of antimicrobial agents andcompositions, quaternary ammonium compounds represent one of the largestof the classes of antimicrobial agents in use. At low concentrations,quaternary ammonium type antimicrobial agents are bacteriostatic,fungistatic, algistatic, sporostatic, and tuberculostatic. At mediumconcentrations they are bactericidal, fungicidal, algicidal, andviricidal against lipophilic viruses. Silicone quaternary ammonium saltcompounds are well known as exemplified by U.S. Pat. No. 3,560,385,issued Feb. 2, 1971, and the use of such compounds as antimicrobialagents is taught, for example, in a wide variety of patents such as U.S.Pat. Nos. 3,730,701, issued May 1, 1973, and 3,817,739, issued June 18,1974, where the compounds are used to inhibit algae; 3,794,736, issuedFeb. 26, 1974 , and 3,860,709, issued Jan. 14, 1975, where they areemployed for sterilizing or disinfecting a variety of surfaces andinstruments; 3,865,728, issued Feb. 11, 1975, where the compounds areused to treat aquarium filters; 4,259,103, issued Mar. 31, 1981; and inBritish Patent No. 1,386,876, of Mar. 12, 1975. Published unexaminedEuropean Application No. 228464 of July 15, 1987, teaches thatmicroorganisms on plants can be killed by the application thereto of anaqueous mixture of a surfactant and an organosilicon quaternary ammoniumcompound. In a particular application of an antimicrobial siliconequaternary ammonium compound, a paper substrate is rendered resistant tothe growth of microorganisms in U.S. Pat. No. 4,282,366, issued Aug. 4,1981. In U.S. Pat. No. 4,504,541, issued Mar. 12, 1985, an antimicrobialfabric is disclosed which is resistant to discoloration and yellowing bytreatment of the fabric with a quaternary ammonium base containing anorganosilicone. U.S. Pat. No. 4,615,937, issued Oct. 7, 1986, as well asits companion U.S. Pat. No. 4,692,374, issued Sept. 8, 1987, relate towet wiper towelettes having an antimicrobial agent substantive to thefibers of the web and being an organosilicon quaternary ammoniumcompound. In a series of Burlington Industries, Inc. U.S. Pat. Nos.4,408,996, issued Oct. 11, 1983, 4,414,268, issued Nov. 8, 1983,4,425,372, issued Jan. 10, 1984, and 4,395,454, issued July 26, 1983,such compounds are disclosed to be useful in surgical drapes, dressings,and bandages. This same assignee also discloses these compounds as beingemployed in surgeons' gowns in U.S. Pat. Nos. 4,411,928, issued Oct. 25,1983, and 4,467,013, issued Aug. 21, 1984. Organosilicon quaternaryammonium compounds have been employed in carpets, in U.S. Pat. No.4,371,577, issued Feb. 1, 1983; applied to walls, added to paints, andsprayed into shoes, in U.S. Pat. No. 4,394,378, issued July 19, 1983;applied to polyethylene surfaces and used in pillow ticking in U.S. Pat.No. 4,721,511, issued Jan. 26, 1988; in flexible polyurethane foams offine-celled, soft, resilient articles of manufacture in U.S. Pat. No.4,631,297, issued Dec. 23, 1986; and mixed with a surfactant in JapaneseKokai Application No. 58-156809, filed Aug. 26, 1983, of Sanyo ChemicalIndustries, Ltd., for the purpose of achieving uniformity ofdistribution of the compounds to a surface. Thus, the versatility ofsuch compositions is readily apparent.

A defoamer or antifoam agent is a material which, when added in lowconcentration to a foaming liquid, controls the foam problem. Thedefoamer equilibriates the rate of foam collapse with the rate of foamformation. Such materials, in addition, remove unsightly and troublesomesurface foam, improve filtration, watering, washing, and drainage, ofvarious types of suspensions, mixtures, and slurries. Defoamers havefound application traditionally in such areas of use as the pulp andpaper industry, paints and latex, coating processes, fertilizers,textiles, fermentation processes, metal working, adhesive, caulk andpolymer manufacture, the sugar beet industry, oil well cement, cleaningcompounds, cooling towers and in chemical processes of varieddescription such as municipal and industrial primary and secondary wastewater treatment facilities. It is essential for a defoamer that it beinert and not capable of reacting with the product or system in which itis used, and that it have no adverse effect on the product or system.The components of a defoamer generally consist of primary and secondaryantifoam agents, a carrier, an emulsifier, and optionally a stabilizingagent. The primary antifoam agent is the main ingredient of the defoamerand includes materials such as hydrophobic silica treated silica, fattyamides, hydrocarbon waxes, and fatty acids and esters. In particular,hydrophobic silica is finely divided silica coated with chemisorbedsilica. The silica is dispersed in hydrocarbon oil and the hydrophobicsilica particles present a low energy silicon surface to the foamedenvironment. In the absence of the hydrocarbon oil, hydrophobic silicaitself has no defoaming capacity. The secondary antifoam agent actssynergistically with the primary antifoam agent and includes suchmaterials as silicones, and fatty alcohols and esters. Carriersfrequently comprise hydrocarbon oils, water, fatty alcohols and esters,and solvents. Emulsifiers such as esters, ethoxylated compounds,sorbitan esters, silicones, and alcohol sulfates, function to spread orintroduce the primary and secondary antifoam agents and the carrier intothe system. Shelf life of defoamers can be improved by stabilizingagents, and often in water-based defoamers, a preservative is added toprevent bacterial spoilage in the drum or shipping container. Suchstabilizing agents have consisted of, for example, oleic acid, hexyleneglycol, fatty alcohols, naphthalene sulfonates, butyl alcohol, andformaldehyde. Dispersion defoamers are finely divided particulates ininsoluble vehicles such as mineral oils, kerosene, fatty alcohols, andsilicone oils. Representative of such dispersion defoamers are, forexample, U.S. Pat. No. 3,652,453, issued Mar. 28, 1972, U.S. Pat. No.3,677,963, issued July 18, 1972, U.S. Pat. No. 3,923,683, issued Dec.2,1975, and U.S. Pat. No. 4,021,355, issued May 3, 1977. The dispersedparticulate has a high surface area such as silica, talc, clay, fattyamides, heavy metal soaps, and high melting point polymeric materials.Representative of such materials is U.S. Pat. No. 2,843,551, issued July15, 1968. Such particulates are treated with silicones, for example, torender them hydrophobic, as taught in U.S. Pat. No. 3,951,883, issuedApr. 20, 1976. Finely divided particles of silica may also be dispersedin polydimethylsiloxane and similar type silicones as taught, forexample, in U.S. Pat. No. 4,400,288, issued Aug. 23, 1983.

As noted above, the defoamers of the prior art have often required theaddition to drums and shipping containers of a preservative such as abiocide in order to prevent bacterial spoilage. This additional andseparate step in the process has often proved to be cumbersome andexpensive, and has not altogether been effective in that it so oftenoverlooked entirely resulting in large batches of spoiled materials.This invention seeks to overcome such difficulties by providing an allinclusive defoamer that requires no separate step of preservativeaddition to drums, shipping and storage containers, but which improveddefoamer includes in the defoamer composition itself, an antimicrobialagent in order to prevent microbiological contamination anddeterioration of drums, shipping containers, and storage containers, ofdefoamer material due to bacterial spoilage. Thus, the defoamer of thepresent invention includes a biologically active and bactericidallyactive component which will combat microorganisms by either destroyingall of the microbes present or preventing their proliferation to numbersthat would be significantly destructive to the system sought to beprotected. Hence, the defoamer of the present invention will not onlyperform its defoaming function but will in addition dispose of organicgrowths, microbes, microorganisms, bacteria, and fungi, by interferingwith the metabolic process of such organisms typically found in defoamerdrums, shipping containers, and storage containers, to provide lethalexposure and an inhibiting and killing action of the bacteriaresponsible for spoilage of such products.

SUMMARY OF THE INVENTION

This invention relates to a defoamer composition including a primaryantifoam agent which includes a particulate-type material having a highsurface area such as silica, a secondary antifoam agent for actingsynergistically with the primary antifoam agent such aspolydimethylsiloxane, a water carrier, and a quaternary ammonium saltsilane compound which functions as an antimicrobial agent, fixed andadhered to the surface of the particulate material, in order that thedefoamer composition be resistant to biological degradation due to thepresence in the system of microorganisms. Methods of defoaming cationic,anionic, and nonionic surfactant produced foams are also disclosed.

The invention also relates to an antifoam composition for destabilizingfoams produced by surfactants comprising a primary antifoam agentincluding a particulate material having a high surface area, a secondaryantifoam agent for acting synergistically with the primary antifoamagent, and an antimicrobial agent being fixed and adhered to the surfaceof the particulate material, the antimicrobial agent being anorganosilane having the general formula selected from the groupconsisting of ##STR1## wherein, in each formula, R is an alkyl radicalof 1 to 4 carbon atoms or hydrogen;

a has a value of 0, 1 or 2;

R' is a methyl or ethyl radical;

R" is an alkylene group of 1 to 4 carbon atoms;

R'", R"" and R^(v) are each independently selected from a groupconsisting of alkyl radicals of 1 to 18 carbon atoms, --CH₂ C₆ H₅, --CH₂CH₂ OH, --CH₂ OH, and --(CH₂)_(x) NHC(O)R^(vi), wherein x has a value offrom 2 to 10 and R^(vi) is a perfluoroalkyl radical having from 1 to 12carbon atoms;

X is chloride, bromide, fluoride, iodide, acetate or tosylate.

Further, the invention relates to a process for destabilizing foamsproduced by cationic, anionic, and nonionic surfactants comprisingadding to the system producing the foams an effective amount of anantifoam composition including a primary antifoam agent comprised of aparticulate material having a high surface area, a secondary antifoamagent for acting synergistically with the primary antifoam agent, and anantimicrobial agent being fixed and adhered to the surface of theparticulate material, the antimicrobial agent being an organosilanehaving the general formula selected from the group consisting of##STR2## wherein, in each formula, Y is R or RO where R is an alkylradical of 1 to 4 carbon atoms or hydrogen;

a has a value of 0, 1 or 2;

R' is a methyl or ethyl radical;

R" is an alkylene group of 1 to 4 carbon atoms;

R'", R"" and R^(v) are each independently selected from a groupconsisting of alkyl radicals of 1 to 18 carbon atoms, --CH₂ C₆ H₅, --CH₂CH₂ OH, --CH₂ OH, and --(CH₂)_(x) NHC(O)R^(vi), wherein x has a value offrom 2 to 10 and R^(vi) is a perfluoroalkyl radical having from 1 to 12carbon atoms;

X is chloride, bromide, fluoride, iodide, acetate or tosylate.

The invention also relates to a method for varying the hydrophobicity ofparticulate silica by treating the silica with the above referred toorganosilane antimicrobial agent in varying amounts in order to fix andadhere to the surface of the particulate silica the organosilaneantimicrobial agent. Thus, the silica is hydrophilic when theorganosilane antimicrobial agent is present in a first amount, whereasin a second amount the silica is hydrophobic. For example, when theratio of the organosilane antimicrobial agent and silica is about 0.1,the silica is hydrophilic. This provides an antimicrobial silane treatedsilica that is easily dispersible in water. At ratios of about 0.25 andabove, however, the silica is hydrophobic. The hydrophobicity of thesilica changes with and is a function of the surface coverage of theorganosilane antimicrobial agent. Thus, the hydrophobicity increasesfrom 0.25 to 4.0 as shown in Table A. This is a distinct advantage sincesilica is typically hydrophobed by tumble blending the silica inhexamethyldisilazane. The tumble blending technique is a non-aqueoussolvent type of treatment, whereas in accordance with the teaching ofthe present invention, the silica can be hydrophobed with either aqueousor non-aqueous solvent treatment methods. Because an aqueous system issafer, less flammable, and environmentally more acceptable, than organicsolvent systems, for example, the benefits of the method of the presentinvention can be appreciated. The silane modified silica surfacesprovided in accordance with the concepts of the herein describedinvention are also durable and non-leachable. In addition to beingantimicrobially active, the surfaces, as noted above, havecharacteristics of hydrophobicity-hydrophilicity that is variable. Incontrast to traditional processes for rendering such surfacehydrophobic, the treatment process of this invention is less complex,and the silica produced thereby is at least equal to if not superior inperformance to otherwise standard varieties of hydrophobic silicas. Thechange in hydrophobicity of the silica in response to the surfacecoverage of the organosilane antimicrobial agent hereinafter referred toas TMS, is more readily apparent from a consideration of the Table A setforth hereinbelow:

                  TABLE A                                                         ______________________________________                                        Ratio of TMS*/Silica                                                          (Percent by Weight)                                                                             Hydrophobic/Hydrophilic                                     ______________________________________                                        0.0               Hydrophilic                                                 0.1               Hydrophilic                                                  0.25             Hydrophobic                                                 0.5               Hydrophobic                                                 1.0               Hydrophobic                                                 2.0               Hydrophobic                                                 4.0               Hydrophobic                                                 ______________________________________                                         *3-(trimethoxysilyl)-propyl dimethyloctadecyl ammonium chloride          

It is therefore an object of the present invention to provide a new typeof defoaming agent in which a separate ingredient of a preservative toprevent bacterial spoilage may be dispensed with, and wherein theparticulate of the defoamer composition has adhered thereto anantimicrobial agent which otherwise acts as the preservative of thecomposition.

It is also an object of the present invention to provide a defoamercomposition which will not only handle the foaming problem effectively,but which will in addition act to prevent system spoilage due to theaction of bacteria.

It is further an object of the present invention to provide an antifoamagent that will destabilize foams produced from cationic, anionic, andnonionic surfactants, and which antifoam agent does not require theseparate addition to the system of another antimicrobial composition inorder to survive in a system contaminated with microorganisms.

The compositions of the present invention act in preventingmicrobiological contamination and deterioration of products, materials,and systems. For example,3-(trimethoxysilyl)propyldimethyloctadecylammonium chloride, hereinreferred to as TMS, is an effective antimicrobial agent in which theactive ingredient hydroylzes in water and reacts with substrates withwhich it is brought into contact. These sebstrates demonstratenonleaching broad spectrum antimicrobial activity. By including such anantimicrobial component in the antifoam composition, the benefits ofboth types of compositions are realized as against both functioningindependently one from the other. Hence, the compositions set forth inthe present invention posses unique features and advantages over stateof the art defoamers in that they are capable of not only destabilizingsurfactant foams but also prevent spoilage of such systems because ofbiological contamination.

These and other features, objects, and advantages, of the presentinvention will become apparent from the following detailed descriptionof the invention.

IN THE DRAWING

FIG. 1 is a graphical representation of the foaming characteristics ofone percent by weight aqueous solutions of three untreated surfactants.The foam height in inches for each surfactant is plotted against time inminutes. The surfactants are TRITON® X-100, a registered trademark for amaterial marketed by Rohm & Haas, Philadelphia, Pa., a nonionicsurfactant of the formula C₈ H₁₇ C₆ H₄ O(CH₂ CH₂ O)₁₀ OH, hereinafterreferred to as TX100; sodium dodecyl sulfate an anionic surfactant ofthe formula CH₃ (CH₂)₁₁ SO₄ Na, hereinafter referred to as SDS; anddodecyltrimethyllammonium bromide a cationic surfactant of the formulaCH₃ (CH₂)₁₁ N(CH₃)₃ Br, hereinafter referred to as DTAB.

FIG. 2 is a graphical representation similar to FIG. 1 except that DTABis shown separatelly and including the antifoam emulsion of the presentinvention showing the effect of the addition of the antifoam. Theantifoam was added in a concentrastion of 0.5 parts per million based onthe weight of silica and polydimethylsiloxane constituents in theantifoam formulation. The four defferently shaded bars indicateformulations wherein the content of the antimicrobial agent of thepresent invention was varied. In the legend, the first set of numbersreading 0.5 corresponds to the concentration of the antifoam referred toabove. whereas the second set of numbers reading 1, 0.5, 0.25, and 0.1,correspond to the ratio of the antimicrobial agent and silica set forthin Table I in the specification.

FIGS. 3 and 4 are the same as FIG. 2 except that FIGS. 3 and 4 arespecific to TX100 and SDS, respectively.

FIG. 5 is a graphical representation illustrating the effect of thechain length of the carbon atoms in the alkyl radical R^(v) group onfoaming. Compounds including C₆, C₁₆, and C₁₈, carbon atom R^(v) chainlengths were employed in systems foamed with TX100 and SDS. The relativefoam height is expressed for each of the C₆, C₁₆, and C₁₈, compoundsemployed in each of the TX100 and SDS systems. The C₁₈ compoundpractically eliminated all foam in the TX100 system and hence is onlyslightly visible in the graphical representation. The higher chainlength compounds C₁₆ and C₁₈ can be seen to be of more effect than thecompound of chain length C₆.

DETAILED DESCRIPTION OF THE INVENTION

Ammonium compounds in which all of the hydrogen atoms have beensubstituted by alkyl groups are called quaternary ammonium salts. Thesecompounds may be represented in a general sense by the formula: ##STR3##

The nitrogen atom includes four covalently bonded substituents thatprovide a cationic charge. The R groups can be any organic substituentthat provides for a carbon and nitrogen bond with similar and dissimilarR groups. The counterion X is typically halogen. Use of quaternaryammonium compounds is based on the lipophilic portion of the moleculewhich bears a positive charge. Since most surfaces are negativelycharged, solutions of these cationic surface active agents are readilyabsorbed to the negatively charged surface. This affinity for negativelycharged surfaces is exhibited by3-(trimethoxysilyl)propyldimethyloctadecyl ammonium chloride of theformula: ##STR4##

In the presence of moisture, this antimicrobial agent imparts a durable,wash resistant, broad spectrum biostatic surface antimicrobial finish toa substrate. The organosilicon quaternary ammonium compound is leachresistant, nonmigrating, and is not consumed by microorganisms. It iseffective against gram positive and gram negative bacteria, fungi algae,yeasts, mold, rot, mildew, and malodor. The silicone quaternary ammoniumsalt provides durable, bacteriostatic, fungistatic, and algistaticsurfaces. It can be applied to organic or inorganic surfaces as a diluteaqueous or solvent solution of 0.1-1.5 percent by weight of activeingredient. After the alkoxysilane is applied to a surface, it ischemically bonded to the substrate by condensation of the silanol groupsat the surface. The compound is a low viscosity, light to dark amberliquid, soluble in water, alcohols, ketones, esters, hydrocarbons, andchlorinated hydrocarbons. The compound has been used in applicationssuch as, for example, socks, filtration media, bed sheets, blankets,bedspreads, carpet, draperies, fire hose fabric materials, humidifierbelts, mattress pads, mattress ticking, underwear, nonwoven disposablediapers, nonwoven fabrics, outerwear fabrics, nylon hosiery, vinylpaper, wallpaper, polyurethane cushions, roofing materials, sand bags,tents, tarpaulins, sails, rope, athletic and casual shoes, shoe insoles,shower curtains, toilet tanks, toilet seat covers, throw rugs, towels,umbrellas, upholstery fiberfill, intimate apparel, wiping cloths, andmedical devices.

The antifoams of the present invention were prepared in accordance withExamples set forth hereinbelow, and in the Examples as well as in theTables, the antimicrobial composition identified as TMS refers to aproduct manufactured by the Dow Corning Corporation, Midland, Mich., asan antimicrobial agent. This compound is3-(trimethoxysilyl)-propyldimethyloctadecyl ammonium chloride referredto above diluted to forty-two percent active ingredients by weight withmethanol.

The antifoams of the present invention were prepared by using quaternaryammonium silane functionalized silicas. The silica employed to preparethe antifoams was QUSO® G35, a silica distributed by North AmericanSilica Company, Teterboro, N.J. The silicas were prepared by refluxingin a polar solvent resulting in a silylation reaction shown below:##STR5## where R=C₁₈ H₃₇, and

X=halogen.

EXAMPLE I

The antifoam formulation of the present invention was prepared bycombining one gram of silica, nine grams of polydimethylsiloxane fluidof a viscosity of about three hundred-fifty centistokes, onehundred-eighty grams of water, and ten grams of METHOCEL®, a product andtrademark of The Dow Chemical Company, Midland, Mich., formethylcellulose. The silica used was QUSO® G 35. The content of thesilica and polydimethylsiloxane fluid was used for calculations relatingto parts per million solids, to the exclusion of the water andmethylcellulose content in the antifoam formulation. The TMSantimicrobial agent content in the antifoam emulsion formulation can beseen by reference to Table I.

                  TABLE I                                                         ______________________________________                                                        Concentration of TMS                                          Ratio of TMS/Silica                                                                           (parts per million)                                           ______________________________________                                        0.10            125                                                           0.25            250                                                           0.50            500                                                           1.00            500                                                           2.00            500                                                           4.00            500                                                           ______________________________________                                    

Silicas used in the preparation of the antifoam emulsions were tested inaccordance with a series of procedures set forth hereinbelow.

The anion of an aqueous sodium salt of bromphenol blue can be complexedwith the cation of polymerized silanes of this invention while on asubstrate. The blue colored complex, substantive to a water rinse, isqualitatively indicative of the presence of the cation on the substratethus indicating the extent of antimicrobial agent on a given substrate.A comparison of the intensity of retained blue color to a color standardis used as a check to determine if the treatment has been appliedproperly and durably.

The method consists of preparing a 0.02 to 0.04 weight percent solutionof bromphenol blue in distilled water. This solution is made alkalineusing a few drops of saturated Na₂ CO₃ solution per 100 milliliters ofthe solution. Two to three drops of this solution are placed on thetreated substrate and allowed to stand for two minutes. The substrate isthen rinsed with copious amounts of tap water and the substrate isobserved for a blue stain and it is compared to a color standard.

For a spectrophotometric determination, the following test is used.

The sodium salt of bromphenol blue is depleted from a standard solutionby complexing with the cations on a treated substrate. The change inbromphenol blue concentration is determined spectrophotometrically or bycomparison with color standards whereby the level of substrate treatmentby the cationic silane is determinable.

The method consists of preparing a 0.02 weight percent standard solutionof bromphenol blue in distilled water. It is made alkaline with a fewdrops of saturated Na₂ CO₃ solution per 100 milliliters of bromphenolblue solution. The color of this solution is purple.

The blank solution is adjusted to yield a 10 to 12% transmittancereading when measured in 1 cm cells using a spectrophotometer set at 589nm by the following method.

Fill a container 3/4 full of distilled water and add 2 ml of the 0.02%standard bromphenol blue solution for every 50 ml of distilled water.Add 0.5 ml of a 1% Triton® X-100 surfactant (manufactured by Rohm andHaas, Philadelphia, PA., U.S.A.) aqueous solution for every 50 ml ofwater. Mix, and using the spectrophotometer, determine the maximumabsorbance. Adjust the upper zero to 100% transmittance with distilledwater. Check the percent transmittance of the working bromphenol bluesolution at the maximum absorbance setting. Adjust the blank solution to10 to 12% transmittance with either water or bromphenol blue standardsolution as necessary.

The samples of treated substrate are tested by placing 0.5 gram samplesof the substrate standards in a flask large enough for substantialagitation of the sample and the test solution. Add 50 ml of the workingsolution. Agitate for 20 minutes on a wrist-action shaker. Fill the testcurvette with the test solution. Centrifuge if particulate matter ispresent. Measure the % transmittance at the wavelength set forth above.The transmittance is compared against a standard curve prepared bypreparing several substrate samples of known concentration of thecationic silane. For example, samples containing a known amount ofcationic silane at, for example, 0%, 0.25%, 0.50%, 0.75% and 1% are readspectrophotometrically and a curve is plotted.

The foregoing bromophenol blue test was conducted using TMS treatedsilica, and the test results can be seen in Table II. In Table II, itcan be seen that the TMS was effectively bound to the treated silica.

                  TABLE II                                                        ______________________________________                                                      BROMOPHENOL BLUE                                                SAMPLE          % T    Color Intensity.sup.1                                  ______________________________________                                        Untreated       23     W                                                      1 part silica   92     P                                                      0.1 part TMS                                                                  1 part silica   96     P                                                      0.25 parts TMS                                                                1 part silica   97     MB                                                     0.5 parts TMS                                                                 1 part silica   92     MB                                                     1.0 parts TMS                                                                 ______________________________________                                         .sup.1 Depth of Blue: P = purple; DB = dark blue; MB = medium blue; LB =      light blue; and W = white.                                               

The silanes useful in this invention have the general formula ##STR6##It should be noted that generically, these materials are quaternaryammonium salts of silanes. Most of the silanes falling within the scopeof this invention are known silanes and references disclosing suchsilanes are numerous. One such reference, U.S. Pat. No. 4,259,103,issued to James R. Malek and John L. Speier, on Mar. 31, 1981, discussesthe use of such silanes to render the surfaces of certain substratesantimicrobial. Canadian Patent No. 1,010,782, issued to Charles A. Rothshows the use of fillers treated with certain silanes to be used inpaints and the like to give antimicrobial effects.

Numerous other publications have disclosed such silanes, namely, A. J.Isquith, E. A. Abbott and P. A. Walters, Applied Microbiology, December,1972, pages 859-863; P. A. Walters, E. A. Abbott and A. J. Isquith,Applied Microbiology, 25, No. 2, p. 253-256, February 1973 and E. A.Abbott and A. J. Isquith, U.S. Pat. No. 3,794,736 issued Feb. 26, 1974,U.S. Pat. No. 4,406,892, issued Sept. 27, 1983, among others.

For purposes of this invention, the silanes can be used neat or they canbe used in solvent or aqueous-solvent solutions. When the silanes areused neat, the inventive process is preferably carried out in a systemin which some small amount of water is present. If it is not possible tohave a system with some small amount of water present, then a watersoluble or water-dispersable, low molecular weight hydrolyzate of thesilane may be used. What is important is the fact that the durability ofany effect produced by the silane as part of a product requires that thesilane molecule react with a surface to a certain extent. The mostreactive species, as far as the silanes are concerned, is the .tbd.SiOHthat is formed by hydrolysis of the alkoxy groups present on the silane.The .tbd.SiOH groups tend to react with the surface and bind the silanesto the surface. It is believed by the inventor even though the primemode of coupling to the surface system is by the route described above,it is also believed by the inventor that the alkoxy groups on thesilicon atom may also participate in their own right to bind to thesurface.

Preferred for this invention is a reactive surface containing some smallamount of water. By "reactive", it is meant that the surface mustcontain some groups which will react with some of the silanols generatedby hydrolysis of the silanes of this invention.

R in the silanes of this invention are alkyl groups of 1 to 4 carbonatoms. Thus, useful as R in this invention are the methyl, ethyl, propyland butyl radicals. In the above formulas RO can also be R. R can alsobe hydrogen thus indicating the silanol form, i.e. the hydrolyzate. Thevalue of a is 0, 1 or 2 and R' is a methyl or ethyl radical.

R" for purposes of this invention is an alkylene group of 1 to 4 carbonatoms. Thus, R" can be alkylene groups such as methylene, ethylene,propylene, and butylene. R'", R"", and R^(v) are each independentlyselected from a group which consists of alkyl radicals of 1 to 18carbons, --CH₂ C₆ H₅, --CH₂ CH₂ OH, --CH₂ OH, and --(CH₂)_(x)NHC(O)R^(vi). x has a value of from 2 to 10 and R^(vi) is aperfluoroalkyl radical having from 1 to 12 carbon atoms. X is chloride,bromide, fluoride, iodide, acetate or tosylate.

Preferred for this invention are the silanes of the general formula##STR7## R is methyl or ethyl; a has a value of zero; R" is propylene;R'" is methyl or ethyl; R"" and R^(v) are selected from alkyl groupscontaining 1 to 18 carbon atoms wherein at least one such group islarger than eight carbon atoms and x is either chloride, acetate ortosylate.

Exemplary compounds are those silanes having the formula

    (CH.sub.3 O).sub.3 Si(CH.sub.2).sub.3 N.sup.⊕ (CH.sub.3).sub.2 C.sub.18 H.sub.37 Cl.sup.- and (CH.sub.3 O).sub.3 Si(CH.sub.2).sub.3 --N.sup.⊕ CH.sub.3 (C.sub.10 H.sub.21).sub.2 Cl.sup.-.

As indicated above, most of these silanes are known from the literatureand methods for their preparation are known as well. See, for example,U.S. Pat. No. 4,282,366, issued Aug. 4, 1981; U.S. Pat. No. 4,394,378,issued July 19, 1983, and U.S. Pat. No. 3,661,963 issued May 9, 1972,among others.

Specific silanes within the scope of the invention are represented bythe formulae:

(CH₃ O)₃ Si(CH₂)₃ N⁺ (CH₃)₂ C₁₈ H₃₇ Cl⁻,

(CH₃ O)₃ Si(CH₂)₃ N⁺ (CH₃)₂ C₁₈ H₃₇ Br⁻,

(CH₃ O)₃ Si(CH₂)₃ N⁺ (C₁₀ H₂₁)₂ CH₃ Cl⁻,

(CH₃ O)₃ Si(CH₂)₃ N⁺ (CH₁₀ H₂₁)₂ CH₃ Br⁻,

(CH₃ O)₃ Si(CH₂)₃ N⁺ (CH₃)₃ Cl⁻,

(CH₃ O)₃ SiCH₂ CH₂ CH₂ P⁺ (C₆ H₅)₃ Cl⁻,

(CH₃ O)₃ SiCH₂ CH₂ CH₂ P⁺ (C₆ H₅)₃ Br⁻,

(CH₃ O)₃ SiCH₂ CH₂ CH₂ P⁺ CH₃)₃ Cl⁻,

(CH₃ O)₃ SiCH₂ CH₂ CH₂ P⁺ (C₆ H₁₃)₃ Cl⁻,

(CH₃)₃ Si(CH₂)₃ N⁺ (CH₃)₂ C₁₂ H₂₅ Cl⁻,

(CH₃)₃ Si(CH₂)₃ N⁺ (C₁₀ H₂₁)₂ CH₃ Cl⁻,

(CH₃)₃ Si(CH₂)₃ N⁺ (CH₃)₂ C₁₈ H₃₇ Cl⁻,

(CH₃ O)₃ Si(CH₂)₃ N⁺ (CH₃)₂ C₄ H₉ Cl⁻,

(C₂ H₅ O)₃ Si(CH₂)₃ N⁺ (CH₃)₂ C₁₈ H₃₇ Cl⁻,

(CH₃ O)₃ Si(CH₂)₃ N⁺ (CH₃)₂ CH₂ C₆ H₅ Cl⁻,

(CH₃ O)₃ Si(CH₂)₃ N⁺ (CH₃)₂ CH₂ CH₂ OHCl⁻, ##STR8## (CH₃ O)₃ Si(CH₂)₃ N⁺(CH₃)₂ (CH₂)₃ NHC(O)(CF₂)₆ CF₃ Cl⁻,

(CH₃ O)₃ Si(CH₂)₃ N⁺ (C₂ H₅)₃ Cl⁻.

X is chlorine in the above specific silanes.

As noted hereinbefore, hydrophobic silica is a component of antifoamagents. The silica surface is hydrophobed by treatment withdimethysiloxanes. In accordance with the present invention, silica istreated with the TMS antimicrobial agent, and the treated silica can besubstituted for the silica of standard and typical antifoam formulationscontaining dimethylsiloxane, water, and silica.

The polydimethylsiloxanes used herein can be high molecular weightpolymers having a molecular weight in the range from about 200 to about200,000, and have a kinematic viscosity in the range from about 20 to2,000,000 mm/s, preferably from about 500 to 50,000 mm/s, morepreferably from about 3,000 to about 30,000 mm/s at 25° C. The siloxanepolymer is generally end-blocked either with trimethylsilyl or hydroxylgroups but other end-blocking groups are also suitable. The polymer canbe prepared by various techniques such as the hydrolysis and subsequentcondensation of dimethyldihalosilanes, or by the cracking and subsequentcondensation of dimethylcyclosiloxanes.

The polydimethylsiloxane is present in combination with particulatesilica. Such combinations of silicone and silica can be prepared byaffixing the silicone to the surface of silica for example by means ofthe catalytic reaction disclosed in U.S. Pat. No. 3,235,509. Foamregulating agents comprising mixtures of silicone and silica prepared inthis manner preferably comprise silicone and silica in a silicone:silicaratio of from 20:1 to 200:1, preferably about 25:1 to about 100:1. Thesilica can be chemically and/or physically bound to the silicone in anamount which is preferably about 0.5% to 5% by weight, based on thesilicone. The particle size of the silica employed in suchsilica/silicone foam regulating agents should preferably be not morethan 100 millimicrons preferably from 10 millimicrons to 20millimicrons, and the specific surface area of the silica should exceedabout 50 m² /g.

Alternatively, silicone and silica can be prepared by admixing asilicone fluid of the type herein disclosed with a hydrophobic silicahaving a particle size and surface area in the range disclosed above.Any of several known methods may be used for making a hydrophobic silicawhich can be employed herein in combination with a silicone as the foamregulating agent. For example, a fumed silica can be reacted with atrialkyl chlorosilane (i.e., "silanated") to affix hydrophobictrialkylsilane groups on the surface of the silica. In a preferred andwell known process, fumed silica is contacted withtrimethylchlorosilane.

A preferred material comprises a hydrophobic silanated (most preferablytrimethylsilanated) silica having a particle size in the range fromabout 10 millimicrons to 20 millimicrons and a specific surface areaabove about 50 m² /g intimately admixed with a dimethyl silicone fluidhaving a molecular weight in the range of from about 500 to about200,000, at a weight ratio of silicone to silanated silica of from about20:1 to about 200:1, preferably from about 20:1 to about 100:1.

Yet another type of material suitable herein comprisespolydimethylsiloxane fluid, a silicone resin and silica. The silicone"resins" used in such compositions can be any alkylated silicone resins,but are usually those prepared from methylsilanes. Silicone resins arecommonly described as "three-dimensional" polymers arising from thehydrolysis of alkyl trichlorosilanes, whereas the silicone fluids are"two-dimensional" polymers prepared from the hydrolysis ofdichlorosilanes. The silica components of such compositions are themicroporous materials such as the fumed silica aerogels and xerogelshaving the particle sizes and surface areas herein-above disclosed.

The mixed polydimethylsiloxane fluid/silicone resin/silica materialsuseful in the present compositions can be prepared in the mannerdisclosed in U.S. Pat. No. 3,455,839. Preferred materials of this typecomprise:

(a) from about 10 parts to about 100 parts by weight of apolydimethylsiloxane fluid having a viscosity in the range from 20 to30,000 mm/s at 25° C.:

(b) 5 to 50 parts by weight of a siloxane resin composed of (CH₃)₃SiO_(1/2) units and SiO₂ units in which the ratio of the (CH₃)₃SiO_(1/2) units to the SiO₂ units is within the range of from 0.6/1 to1.2/1: and

(c) 0.5 to 5 parts by weight of a silica aerogel. Such mixtures can alsobe sorbed onto and into a water-soluble solid.

In any event, and in accordance with the present invention, what isprovided is a basic defoamer formulation as outlined above, with thenovel addition of an antimicrobial agent fixed and adhered to thesurface of the silica. With such an antimicrobial agent in place on thesilica, the preservative of prior art defoamer formulations may beeliminated, and the defoamers of the present invention will destabilizefoams produced from surfactants but without the necessity of theaddition of an antimicrobial agent to the system as a separateingredient in order to protect the system from contamination bymicroorganisms.

Antifoam compositions prepared in accordance with the present inventionwere tested in order to demonstrate their defoaming capabilities and todetermine the effectiveness of the antifoam compositions in inhibitingbiological degradation.

In the defoaming tests, three surfactants were selected and the foamingcharacteristics of each of the selected surfactants was determinedinitially without treatment with the antifoam emulsion of the presentinvention, and then each of the selected surfactants was testedseparately including the antifoam emulsion of the present invention. Thedata from these tests is presented in FIG. 1, which is a graphicalrepresentation of the foaming characteristics of one percent aqueoussolutions of the three selected untreated surfactants. The foam heightin inches for each surfactant is plotted against time in minutes. Theselected surfactants are TRITON® X-100, a registered trademark for amaterial marketed by Rohm & Haas, Philadelphia, Pa., a nonionicsurfactant of the formula C₈ H₁₇ C₆ H₄ O(CH₂ CH₂ O)₁₀ OH, hereinafterreferred to as TX100; sodium dodecyl sulfate an anionic surfactant ofthe formula CH₃ (CH₂)₁₁ SO₄ Na, hereinafter referred to as SDS; anddodecyltrimethylammonium bromide, a cationic surfactant of the formulaCH₃ (CH₂)₁₁ N(CH₃)₃ Br, hereinafter referred to as DTAB. Followingtesting of the individual untreated surfactants, each surfactant wasmixed with varying amounts of the antifoam emulsion of the presentinvention, and the defoaming capabilities of the antifoam emulsions ofthe present invention is graphically depicted in FIGS. 2-4. FIG. 2 issimilar to FIG. 1 except that the surfactant DTAB is shown separately aswell as the effect on foaming of the addition of the antifoamcomposition of the present invention. The antifoam is added in aconcentration of 0.5 parts per million based on the weight of silica andpolydimethylsiloxane constituents in the antifoam formulation, and thisinteger appears in the legend as representative of the antifoamconcentration for each shaded area. The four shaded bars in the legendalso indicate concentrations of the antimicrobial agent in the antifoamformulation wherein it can be seen that the content of the TMSantimicrobial agent of the present invention was varied. The integersranging from 0.25 to 1 are representative of the TMS/Silica ratios shownin Table I. FIGS. 3 and 4 are the same as FIG. 2 except that FIGS. 3 and4 are specific to TX100 and SDS, respectively.

The data used to compile FIGS. 1-5 in the drawing were obtained by ashake test employing a mechanical shaker. One hundred milliliters of aone percent by weight solution of surfactant was placed in a fivehundred milliliter bottle, and the desired amount of antifoam was added,typically in the parts per million range. The bottle was shaken for fiveminutes and the foam measured visually with a ruler, both initially andat five minute intervals thereafter for one hour. The same test was usedin order to determine the foam heights in FIG. 1 for the untreatedsurfactants, in which case, no antifoam was added to the bottle.

In FIG. 5 there will be seen the effect of varying the chain length ofthe carbon atoms in the alkyl radical R^(v) group on foaming. Compoundsincluding C₆, C₁₆, and C₁₈, carbon atom R^(v) chain lengths wereemployed in systems foamed with TX100 and SDS. The higher chain lengthcompounds C₁₆ and C₁₈ can be seen to be of more effect than the compoundof chain length C₆.

For example, in U.S. Pat. No. 4,395,352, issued July 26, 1983, there isdisclosed the treatment of silica with silicones where the alkyl groupshave 1-8 carbon atoms. The '352 patent references four other U.S.patents regarding the preparation of such solids, namely; U.S. Pat. Nos.2,802,850; 3,634,288; 3,649,588; and 3,953,487. The '850 patent teachesmethyl trichlorosilane which is not antimicrobial and is not anorganosilicon quaternary ammonium compound. The '288 and '588 patentsboth relate to siloxanes rather than silanes, and the '487 patentdiscloses a silane with alkyl groups of 1-4 carbon atoms.

In contrast, and as is apparent from FIG. 5, the antimicrobialorganosilicon quaternary ammonium compounds of the present inventioncontaining in the alkyl group carbon chain lengths of C₁₆ and C₁₈, havebeen shown to be more effective in reducing foam than the correspondingcompounds containing shorter chain lengths of the order of about sixcarbon atoms. These shorter carbon atom chain lengths are typical of thecompounds found in the '352 patent.

The structure of each of the three exemplary compounds tested in FIG. 5is shown as follows: ##STR9##

In light of FIG. 5, and in view of the foregoing discussion regardingthe '352 patent, it should be apparent that the higher chain lengthcompounds are the most preferred embodiments of the present invention.Thus, the range C₁₂ -C₁₈ is the most preferred range, in particular C₁₆and C₁₈, in contrast to the shorter C₁ -C₈ chains taught by the '352patent.

It can be seen from FIGS. 1-5 that the antifoam composition of thepresent invention broke the foam at a rapid rate and in addition, theantifoam composition of the present invention possesses the addedbenefit in that it is antimicrobial in nature as shown below.

The antimicrobial activity of a treated surface is evaluated by shakinga sample weighing 0.75 grams in a 750,000 to 1,500,000 count Klebsiellapneumoniae suspension for a one hour contact time. The suspension isserially diluted, both before and after contact, and cultured. Thenumber of viable organisms in the suspensions is determined. The presentreduction based on the original count is determined. The method isintended for those surfaces having a reduction capability of 75 to 100%for the specified contact time. The results are reported as the percentreduction.

Media used in this test are nutrient broth, catalog No. 0003-01-6 andtryptone glucose extract agar, catalog No. 0002-01-7 both available fromDifco Laboratories, Detroit, Mich., U.S.A. The microorganism used isKlebsiella pneumoniae American Type Culture Collection; Rockville, Md.U.S.A., catalog No. 4352.

The procedure used for determining the zero contact time counts iscarried out by utilizing two sterile 250 ml. screw-cap Erlenmeyer flasksfor each sample. To each flask is added 70 ml of sterile buffersolution. To each flask is added, aseptically, 5 ml of the organisminoculum. The flasks are capped and placed on a wrist action shaker.They are shaken at maximum speed for 1 minute. Each flask is consideredto be at zero contact time and is immediately subsampled by transferring1 ml of each solution to a separate test tube containing 9 ml of sterilebuffer. The tubes are agitated with a vortex mixer and then 1 ml of eachsolution is transferred to a second test tube containing 9 ml of sterilebuffer. Then, after agitation of the tubes, 1 ml of each tube istransferred to a separate sterile petri dish. Duplicates are alsoprepared. Sixteen ml of molten (42° C.) tryptone glucose extract agar isadded to each dish. The dishes are each rotated ten times clockwise andten times counterclockwise. The dishes are then incubated at 37° C. for24 to 36 hours. The colonies are counted considering only those between30 and 300 count as significant. Duplicate samples are averaged. Theprocedure used for determining the bacterial count after 1 hour isessentially the same as that used to determine the count at the zerocontact time. The only difference is that pour plating is performed atthe 10⁰ and 10⁻¹ dilutions as well as at the 10⁻² dilution. "Percentreduction" is calculated by the formula ##EQU1## where A is the countper milliliter for the flask containing the treated substrate; B is zerocontact time count per milliliter for the flask used to determine "A"before the addition of the treated substrate and C is zero contact timecount per milliliter for the untreated control substrate.

The microbiological efficacy of the TMS treated silica compositions ofthe present invention was determined as outlined above. Theantimicrobial activity was evaluated by shaking samples in Klebsiellapneumoniae suspension for a one hour contact time. The suspension wasserially diluted both before and after contact and cultured. The numberof viable organisms in the suspensions was determined. The percentreduction based on the original count was also determined. The resultsof the antimicrobial activity dynamic surface testing indicated that thecompositions are antimicrobially active in their nature and function,and the microorganisms were substantially reduced in number. The resultsare shown in Table 3.

                  TABLE III                                                       ______________________________________                                        Sample         Percent Reduction                                              ______________________________________                                        Untreated       0                                                             1 part silica  100                                                            0.1 part TMS                                                                  1 part silica  100                                                            0.25 parts TMS                                                                1 part silica  100                                                            0.5 parts TMS                                                                 1 part silica  100                                                            1.0 parts TMS                                                                 ______________________________________                                    

In order to demonstrate the biological efficacy of the antifoamemulsions, a separate test was conducted in order to confirm theiractivity, in addition to and in contrast to the foregoing test on theTMS treated silica which is a constituent of the antifoam emulsion. Inthe antifoam emulsion test, silica with saturation coverage of TMS wasused at a level of 0.5% by weight based on the total antifoam emulsionformulation. The emulsion was tested by a repeated insult antimicrobialtest used to evaluate "in-can" storage preservation of the antifoamemulsion. The inoculum was a mixture of 24 hour shake cultures at 32degrees Centigrade in nutrient broth of Pseudomonas aeruginosa,Pseudomonas fluorescens, and Pseudomonas putida. These organisms werefresh isolates from field contaminated antifoams. They were identifiedby API 20E®, Analytical Products, Plainview, N.Y. The mixed culture wasdiluted in phosphate buffer to deliver a concentration of 10⁸/milliliter of organisms in fifty milliliter aliquots of test antifoams.These were shaken and incubated at thirty-two degrees Centigrade. At theend of twenty-four hours, swab streaks of the samples were made ontryptic soy agar plates. These plates were incubated at thirty-twodegrees Centigrade and read for growth at twenty-four and forty-eighthour intervals. The above inoculum preparation and insult protocols wererepeated at three day intervals for three repetitions per sample, andthe results are shown in Table IV, indicating no growth on the treatedantifoam.

                  TABLE IV                                                        ______________________________________                                                     INSULT.sup.A                                                     SAMPLE         1           2     3                                            ______________________________________                                        Treated antifoam                                                                             -           -     -                                            Untreated antifoam                                                                           +           +     +                                            ______________________________________                                         .sup.A - = no growth  + = growth                                         

The particulate material of the antifoam composition of the presentinvention has been illustrated by means of silica, but it should beunderstood that other equivalent particulate materials may be used inaccordance with the present invention. Thus, for example, there can beused in place of or in addition to silica, high surface areaparticulates such as crushed quartz, aluminum oxide, zirconium silicate,aluminum silicate, magnesium oxide, zinc oxide, talc, diatomaceousearth, iron oxide, calcium carbonate, clay, titania, zirconia, mica,ground glass, glass fiber, sand, carbon black, graphite, barium sulfate,zinc sulfate, wood flour, cork, fluorocarbon polymer powder, rice hulls,and ground peanut shells. The term "silica" as used herein is intendedto include, for example, silica such as fumed silica, precipitatedsilica, and treated silica such as fumed silica and precipitated silicathat has been reacted with an organohalosilane, a disiloxane, ordisilizane.

While the antifoam compositions of the present invention are of generalutility, there may be specifically mentioned by way of application theiruse in the petroleum and petrochemical industry such as in gas-oilseparators, atmospheric and vacuum distillation units, thermal crackingoperations, natural gas treatments, solvent extraction processes,lubricating oils, and asphalt. In the chemical process industry, theantifoams find application in resin manufacture, synthetic rubbermanufacture, vegetable oil processing, starch manufacture, plasticsmanufacture, and fermentation processes. In the textile industry theremay be mentioned synthetic fiber manufacture, dyeing baths, sizingbaths, and latex backing. The food industry includes jams and jellies,cooking oils, dietetic soft drinks, instant coffee, and winemaking. Theantifoams are applicable in the manufacture of antibiotics, and in thepaper industry find utility in pulp manufacture, paper making and papercoating.

It will be apparent from the foregoing that many other variations andmodifications may be made in the structures, compounds, compositions,articles of manufacture, and methods described herein without departingsubstantially from the essential features and concepts of the presentinvention. Accordingly, it should be clearly understood that the formsof the invention described herein are exemplary only and are notintended as limitations on the scope of the present invention.

That which is claimed is:
 1. In an antifoam for destabilizing foamsproduced by surfactants including a particulate material having a highsurface area, the improvement comprising an antimicrobial agentchemically bonded to the surface of the particulate material, theantimicrobial agent being an organosilane having the general formulaselected from the group consisting of ##STR10## wherein, in eachformula, R is an alkyl radical of 1 to 4 carbon atoms or hydrogen;a hasa value of 0, 1 or 2; R' is a methyl or ethyl radical; R" is an alkylenegroup of 1 to 4 carbon atoms; R'" and R"" are each independentlyselected from the group consisting of alkyl radicals of 1 to 18 carbonatoms, --CH₂ C₆ H₅, --CH₂ CH₂ OH, --CH₂ OH, and --(CH₂)_(x)NHC(O)R^(vi), wherein x has a value of from 2 to 10 and R^(vi) is aperfluoroalkyl radical having from 1 to 12 carbon atoms; R^(v) isselected from the group consisting of alkyl radicals of 16 or 18 carbonatoms, --CH₂ C₆ H₅, --CH₂ CH₂ OH, --CH₂ OH, and --(CH₂)_(x)NHC(O)R^(vi), wherein x has a value of from 2 to 10 and R^(vi) is aperfluoroalkyl radical having from 1 to 12 carbon atoms; and X ischloride, bromide, fluoride, iodide, acetate or tosylate.
 2. Theantifoam of claim 1 wherein the particulate material is silica.